diff --git a/pkg/exchange/ftx/stream.go b/pkg/exchange/ftx/stream.go
index f5792912a..e1bfb7c31 100644
--- a/pkg/exchange/ftx/stream.go
+++ b/pkg/exchange/ftx/stream.go
@@ -2,29 +2,48 @@ package ftx
 
 import (
 	"context"
+	"fmt"
 	"sync/atomic"
 	"time"
 
+	"github.com/gorilla/websocket"
+
+	"github.com/c9s/bbgo/pkg/service"
 	"github.com/c9s/bbgo/pkg/types"
 )
 
+const endpoint = "wss://ftx.com/ws/"
+
 type Stream struct {
 	*types.StandardStream
 
-	wsService *WebsocketService
+	ws *service.WebsocketClientBase
 
-	// publicOnly must be accessed atomically
+	// publicOnly can only be configured before connecting
 	publicOnly int32
+
+	key    string
+	secret string
+
+	subscriptions []websocketRequest
 }
 
 func NewStream(key, secret string) *Stream {
-	wss := NewWebsocketService(key, secret)
 	s := &Stream{
+		key:            key,
+		secret:         secret,
 		StandardStream: &types.StandardStream{},
-		wsService:      wss,
+		ws:             service.NewWebsocketClientBase(endpoint, 3*time.Second),
 	}
 
-	wss.OnMessage((&messageHandler{StandardStream: s.StandardStream}).handleMessage)
+	s.ws.OnMessage((&messageHandler{StandardStream: s.StandardStream}).handleMessage)
+	s.ws.OnConnected(func(conn *websocket.Conn) {
+		for _, sub := range s.subscriptions {
+			if err := conn.WriteJSON(sub); err != nil {
+				s.ws.EmitError(fmt.Errorf("failed to send subscription: %+v", sub))
+			}
+		}
+	})
 	return s
 }
 
@@ -35,7 +54,7 @@ func (s *Stream) Connect(ctx context.Context) error {
 		s.subscribePrivateEvents()
 	}
 
-	if err := s.wsService.Connect(ctx); err != nil {
+	if err := s.ws.Connect(ctx); err != nil {
 		return err
 	}
 
@@ -43,28 +62,33 @@ func (s *Stream) Connect(ctx context.Context) error {
 }
 
 func (s *Stream) subscribePrivateEvents() {
-	s.wsService.Subscribe(
-		newLoginRequest(s.wsService.key, s.wsService.secret, time.Now()),
+	s.addSubscription(
+		newLoginRequest(s.key, s.secret, time.Now()),
 	)
-	s.wsService.Subscribe(websocketRequest{
+	s.addSubscription(websocketRequest{
 		Operation: subscribe,
 		Channel:   privateOrdersChannel,
 	})
-	s.wsService.Subscribe(websocketRequest{
+	s.addSubscription(websocketRequest{
 		Operation: subscribe,
 		Channel:   privateTradesChannel,
 	})
 }
 
+func (s *Stream) addSubscription(request websocketRequest) {
+	s.subscriptions = append(s.subscriptions, request)
+}
+
 func (s *Stream) SetPublicOnly() {
 	atomic.StoreInt32(&s.publicOnly, 1)
 }
 
 func (s *Stream) Subscribe(channel types.Channel, symbol string, _ types.SubscribeOptions) {
 	if channel != types.BookChannel {
-		// TODO: return err
+		logger.Errorf("only support orderbook channel")
+		return
 	}
-	s.wsService.Subscribe(websocketRequest{
+	s.addSubscription(websocketRequest{
 		Operation: subscribe,
 		Channel:   orderBookChannel,
 		Market:    TrimUpperString(symbol),
@@ -72,8 +96,9 @@ func (s *Stream) Subscribe(channel types.Channel, symbol string, _ types.Subscri
 }
 
 func (s *Stream) Close() error {
-	if s.wsService != nil {
-		return s.wsService.Close()
+	s.subscriptions = nil
+	if s.ws != nil {
+		return s.ws.Conn().Close()
 	}
 	return nil
 }
diff --git a/pkg/exchange/ftx/websocket.go b/pkg/exchange/ftx/websocket.go
deleted file mode 100644
index ec3f446fe..000000000
--- a/pkg/exchange/ftx/websocket.go
+++ /dev/null
@@ -1,60 +0,0 @@
-package ftx
-
-import (
-	"fmt"
-	"time"
-
-	"github.com/gorilla/websocket"
-
-	"github.com/c9s/bbgo/pkg/service"
-)
-
-type WebsocketService struct {
-	*service.WebsocketClientBase
-
-	key    string
-	secret string
-
-	subscriptions []websocketRequest
-}
-
-const endpoint = "wss://ftx.com/ws/"
-
-func NewWebsocketService(key string, secret string) *WebsocketService {
-	s := &WebsocketService{
-		WebsocketClientBase: service.NewWebsocketClientBase(endpoint, 3*time.Second),
-		key:                 key,
-		secret:              secret,
-	}
-	s.OnConnected(func(_ *websocket.Conn) {
-		if err := s.sendSubscriptions(); err != nil {
-			s.EmitError(err)
-		}
-	})
-	return s
-}
-
-func (w *WebsocketService) Subscribe(request websocketRequest) {
-	w.subscriptions = append(w.subscriptions, request)
-}
-
-var errSubscriptionFailed = fmt.Errorf("failed to subscribe")
-
-func (w *WebsocketService) sendSubscriptions() error {
-	conn := w.Conn()
-	for _, s := range w.subscriptions {
-		if err := conn.WriteJSON(s); err != nil {
-			return fmt.Errorf("can't send subscription request %+v: %w", s, errSubscriptionFailed)
-		}
-	}
-	return nil
-}
-
-// After closing the websocket connection, you have to subscribe all events again
-func (w *WebsocketService) Close() error {
-	w.subscriptions = nil
-	if conn := w.Conn(); conn != nil {
-		return conn.Close()
-	}
-	return nil
-}